Achieving the American Dream (Dramatic Irony)
Vance tells the story of how his grandparents achieved economic stability and managed to escape the vicious circle of Appalachian poverty by moving to Ohio. Ironically, however, this theoretical move towards the American Dream did not solve their problems—in fact, it made them worse. Once the family achieved economic stability, Mamaw and Papaw began fighting, often becoming violent with one another and even threatening to kill each other. The irony of their decision to better their lives by moving, yet in doing so, isolating themselves from the family support they needed and thus seeding conflict that often erupted in brutality, fits into Vance's argument about the mythical nature of the American Dream.
Vicious Circle of Violence (Dramatic Irony)
Papaw and Mamaw did everything they could to take care of their children, but they simultaneously became abusive to one another. As a result, their children had problems in adulthood, getting caught in abusive marriages and abusing drugs. Ironically, despite giving their children a bad example as far as marital dynamics, they were surprised to see that their children followed their example.
Writing This Book (Situational Irony)
Vance declares on the first page of his book that he finds the idea that the book exists patently absurd, since, in his view, he has accomplished nothing so extraordinary. This is ironic: since the first sentence in the book that Vance publishes is a statement that works to (nominally) negate the value of the book itself: one would imagine that a writer wouldn't view his own work as absurd or nonremarkable.
The loss of work at Armco (Dramatic Irony)
It is ironic that Armco is eventually taken for granted by the children of its employees, who are surprised to find they cannot get a job there. This is ironic because most of their parents took jobs at the company so that their children could have white-collar jobs, yet those children fail to work hard enough to get even the job their parents had.